| 摘要 |
<p>PURPOSE:To clear a random access memory RAM only when needed and to improve the reliability of a controller containing a RAM, by short-circuiting the resistance of a resetting circuit of a microcomputer via a connector of a back-up battery. CONSTITUTION:When a back-up power supply 17 is connected to a one-chip microcomputer 13 via a connector 18, a resistance 14 forming a resetting circuit for control computer 13 together with a capacitor 15 is short-circuited via the connector 18. Therefore no time constant action is carried out by a capacitor 15 and the resistance 14 when a DC power supply 11 is turned on again after once turned off. Then the voltage of the reset terminal of the computer 13 rises up immediately and is not reset. Thus the contents of the RAM of the computer 13 so far backed up by the power supply 17 are not cleared. When the power supply 11 is turned on again in case of without back-up supply 11 is turned on again in case of without back-up power supply 17, while the reset terminal voltage is rising up gradually in the rate of time constant specified by the resistance 14 and the capacitance, said reset terminal voltage is kept lower than a specified voltage for a specified time. Then the inaccurate RAM contents which disappear partly in a break mode of the power supply 11 are cleared in response to said low voltage of the reset terminal. This improves the reliability of a controller containing a RAM.</p> |
